Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

How to pick a random number from 1-10

torvaney.github.io

Post reply on HN
Print view View original

111–120 of 183 posts

Re: How to pick a random number from 1-10

#111

Post by pvinis »

codetrotter wrote: post #56

> The easy thing to do is to ask someone “Hey, pick a random number from 1 to 10!”. The person replies “7!”. Seven factorial is way bigger than 10. Just kidding, sorry. But what I was actually going to say was, when I read the title of the post, before clicking through, I decided to think of a number myself and I chose the number seven. So it was fun to see that same number in the article. 10% chance in theory and in…

Haha wow!

Ok so I thought of the same. Let me think of a number before clicking.

Then I thought let me try something fancier, I know I would go around 6-8 so let’s switch it up. Let’s put the scale like 5 6 7 8 9 10 1 2 3 4 5 in my mind. Ok now let’s pick from a weird place, like the first half, say the middle of it. What’s that number. Oh it’s 7. I arrived to the same number while trying not to. Different kind of “randomness” I guess.

Humans are weird! :p

Re: How to pick a random number from 1-10

#112

Post by ajuc »

In similar situation (we were playing RPG while on a trip, and we needed to "throw dice") - we simply had the DM count silently and the player that was "throwing" say "STOP".

It was pretty much uniform.

Re: How to pick a random number from 1-10

#113

Post by testplzignore »

If you have a pair of scissors or are willing to ask people to take a brief bit of pain...

Hair.

Cut (or pull) off a chunk of hair from everyone in the room. Put in a big pile. You'll have hundreds of thousands of hairs. It will be a glorious mess :)

Now ask people in the room to grab a handful of the hairs and count them. Take the last digit of the each count - there's your random number. You could maybe get multiple digits from a single handful - just be aware of Benford's law.

Re: How to pick a random number from 1-10

#114

Post by ComputerGuru »

harryh wrote: post #53
roberto wrote: post #52

Earlier quoted context omitted.

What about Benford's Law?

Benford's concerns the first digit, not the last digit.

Except in a distribution that doesn’t go past one digit, of course (no, really, it isn’t that rare to be able to apply Benford’s irl to sequences that don’t go past ten). But, yeah, not applicable in this case.

Re: How to pick a random number from 1-10

#115

Post by jsf01 »

badfrog wrote: post #71
justinpombrio wrote: post #25

...or just add up the answers mod 10. This has the property that if even a single person answers uniformly at random, then the final number you compute will be uniformly random, regardless of how everyone else answers.

> ...or just add up the answers mod 10. This is how my board game groups pick the first player.

How do you prevent the last person to select a number from deciding who goes first?

Re: How to pick a random number from 1-10

#116

Post by dorgo »

OscarCunningham wrote: post #86
throwaway287391 wrote: post #59

Earlier quoted context omitted.

> This has the property that if even a single person answers uniformly at random Has any human ever proven they're capable of this? Generating truly random sequences is more or less impossible for humans AFAIK. (E.g., see https://news.ycombinator.com/item?id=19336754 which challenges you to do just that. Spoiler: you will probably fail miserably.) It's an interesting idea, but in practice I think relying on the assum…

"Just use your free will" https://github.com/elsehow/aaronson-oracle

No free will needed. You see the predictions. Let the model learn and then change your sequence. It takes some time for the model to adjust. This way you can get the prediction rate to 50% or below.

Re: How to pick a random number from 1-10

#117

Post by benj111 »

So this relies on that being a somewhat normal distribution (7 being the most common number).

What if the people were primed by the first person saying 7? What if the first person had said 3?

So really you'd need to get your 'random' numbers, check the distribution, than redistribute your 'random' numbers. Which doesn't seem random or 'random' to me.

Re: How to pick a random number from 1-10

#118

Post by simonh »

jsf01 wrote: post #115
badfrog wrote: post #71

Earlier quoted context omitted.

> ...or just add up the answers mod 10. This is how my board game groups pick the first player.

How do you prevent the last person to select a number from deciding who goes first?

Just ask everyone to write their number down and reveal at the same time.

Re: How to pick a random number from 1-10

#119

Post by quietbritishjim »

gkfasdfasdf wrote: post #90

There is a simple way to generate random numbers in your head: https://groups.google.com/forum/#!msg/sci.math/6BIYd0cafQo/U...

For ease of reference, here is the text at that link verbatim:

Choose a 2-digit number, say 23, your "seed".

Form a new 2-digit number: the 10's digit plus 6 times the units digit.

The example sequence is 23 --> 20 --> 02 --> 12 --> 13 --> 19 --> 55 --> 35 --> ...

and its period is the order of the multiplier, 6, in the group of residues relatively prime to the modulus, 10. (59 in this case).

The "random digits" are the units digits of the 2-digit numbers, ie, 3,0,2,2,3,9,5,... the sequence mod 10. The arithmetic is simple enough to carry out in your head.

This is an example of my "multiply-with-carry" random number generator, and it seems to provide quite satisfactory sequences mod 2^32 or 2^64 , particularly well suited to the way that modern CPU's do integer arithmetic.

You may choose various multipliers and moduli for examples of random selection of the types you ask about.

A description of the multiply-with-carry method is in the postscript file mwc1.ps, included in

The Marsaglia Random Number CDROM with

The DIEHARD Battery of Tests of Randomness,

available at

http://stat.fsu.edu/pub/diehard/

George Marsaglia

Re: How to pick a random number from 1-10

#120

Post by testplzignore »

justinpombrio wrote: post #25

...or just add up the answers mod 10. This has the property that if even a single person answers uniformly at random, then the final number you compute will be uniformly random, regardless of how everyone else answers.

Paradoxically, this may be the best answer because it is not the best answer.

In a room of 8500 people, it is likely that there is someone in the room smarter than you and knows a better way to pick random numbers. Come into the room and tell everyone that your objective is to pick a random number from 1-10. Maybe even go as far as to tell them your mod 10 idea. Wait a bit to let them to think about it, then start asking for the random numbers. It is likely that someone will have come up with a better way to pick a random number than your mod 10 solution, and thus their answer will be more uniformly random that what your solution can produce. And thus your solution becomes at least as uniformly random as theirs.

Post reply on HN